1. Field of the Invention
The structure of this invention resides in the area of pelletizing rolls and more particularly relates to a device for the continuous melting, shearing and pelletizing of material.
2. Description of the Prior Art
Conventional roll mills are well known in the art for mixing amounts of dry blended materials which are delivered into the nip of the rollers. Such roll mills can be heated to melt resins in the mixture and blend the mass of materials to form a sheet around the roll with a buildup of material forming over the nip where great forces shear the materials together to form a homogeneous mass. This type of mixing is highly desirable and is often superior to other forms of material mixing. The sheets that come off the rollers can be cut by a knife and then this material can be passed into step mills, crushers or other devices to particulate the material. Also known in the prior art are pellet mills which can have a ring die where materials are fed inside the ring, usually in the form of raw materials such as powder mixtures to be melted and blended together, and the die can rotate with the material, which is held against the inner sides of the ring by centrifugal force, forced between the holes in the ring by two internal rollers. The material forced through the holes is then cut away from the outside of the ring by a knife positioned against the circumference of the ring thus forming pellets whose dimensions depend upon the speed of the roller and the distance of the pellets' extrusion before the extruded pellet material strikes the knife. Pellet mills are often continuous operation devices. While pellet mills can make pellets out of material, they do not have mixing or shearing capabilities that roll mills have. Roll mills, on the other hand, as they are currently utilized, mix and shear but do not make pellets nor do they process material continuously as a pellet mill can. One example of a structure that acts as a pelletizer with some of the features of a roll mill but which does not mix or shear the material is disclosed in U.S. Pat. No. 2,833,481 to Perks which is a method of breaking compressed acetylene black. Disclosed in this patent is the method wherein lumps of material in a hopper to be broken up are fed to rolls counterrotating against one another and which rolls have therein a screen surface through which the pellets are broken and which pellets can fall inside the rolls. In U.S. Pat. No. 271,589 to Anderson, it is disclosed that wheels can have a surface upon which a product is dispensed which wheels move against one another, forcing portions of the product through slots. Internal cutters then cut away the product from inside the wheel to create smaller particles thereof. In the same vein, in U.S. Pat. No. 1,327,254 to Remmers, peelings are obtained through apertures in the sides of rotating foraminous cylinders which cylinders are disposed at an angle so that the peelings pass out from one end of the cylinder. Also in U.S. Pat. No. 909,133 to Baur, cylinders are provided with apertures therein which apertures are smaller on the exterior of the cylinder and widen to the interior of the cylinder for receiving materials to be crushed and mixed where such material is rolled, kneaded and foreign substances crushed, the walls of the cylinders having holes through which the material is pressed and the material is thereby processed which device is particularly suited for crushing and mixing loam and the like.